Lubricant



Patented Nov. 22, 1938 j UNITED STATES PATENT OFFICE 2,137,783 LUBRICANT tion of Delaware No Drawing. Application April 14, 1937, Serial No. 136,860

14 Claims.

-This invention relates to lubricants, and more particularly togcompositions capable of providing efficient lubrication under conditions of extreme pressure and at the same time having a stability which enables them to resist unusually high temperatures.

This application is a continuation in part of application Serial No. 649,734, filed December 31, 1932, and application Serial No. 737,070, filed July 26, 1934. It is a particular object of this invention to provide safe and eificient lubrication to relatively moving metallic surfaces acting with intersurface pressures which may be considerably in excess of 10,000 pounds per square inch. Such pressures are now commonly encountered in hypold gears, bearings, and contact surfaces of cylinders and piston rings in internal combustion engines, and are becoming more prevalent with ad- 'vances in modern machine design.

related ends said invention then consists of the means hereinafter fully described and particularly pointed out in the claims. The following description sets forth in detail certain approved combinations of ingredients embodying my invention, such disclosed means constituting, however, but certain of various forms. in which the principle of the invention may be used.

Broadly stated, this invention comprises a new lubricant comprising halogenated diphenyl ether (diphenyl oxide) or a halogen-bearing derivative of diphenyl ether as a primary or minor constituent when used in conjunction with lubricating oils, or, for certain purposes, as the sole lubricant. The term, the diphenylethers as used herein and in the claims is intended to include the various derivatives having the diphenyl ether nucleus as well as diphenyl ether itself.

Halogenated diphenyl eth'er is an unusually stable organic ring compound which has been found to be not only a very effective extreme pressure addition agent to lubricating oils, generally the usual mineral oil lubricants, but also an eflicient and desirable lubricant when used as'the sole constituent under certain circumstances.

It is believed that thehalogenated diphenyl ether reacts chemically or physio-chemically with the metallic surfaces to form a non-fluxing surface which will not seize or score. This inven tion is not intended to be limited, however, by any particular theory or'explanation of the action upon the metallic surfaces.

When used in conjunction with a lubricating oil an amount from about .1% and sometimes less'to about 20% of the addition agent, based on the amount of oil, and often about 2% or less, is all that is required to render the finished lubricant efflcient under conditions of extreme pressure. In the case of gear lubricants, for example, somewhat larger quantities, from about 2% to about 10%, may often be preferred but ordinary crankcase oils generally require no more than the lesser quantities indicated above, viz., about .1% to about 2%. When however, the particular use makes desirable a higher percentage of the socalled addition agent, the diphenyl ether may, as previously indicated, be employed in a substantially pure state or with any such proportion of lubricating oil as may be required to afford the characteristics desired; as, for example, high specific gravity, resistance to high temperatures, etc. When thus used as the major or primary constituent of the lubricating composition, halogenated diphenyl oxide has proven very satisfactory due to its eifectiveness combined with unusual stability, general resistance to decomposition, and ability to form high viscosity liquids.

Diphenyl ether may be easily halogenated so that the average halogen content of the product is about six atoms of halogen per molecule; This product provides a very eflicient extreme pressure lubricant and quite small amounts in combination with a lubricating oil are all that are required. A mixture of-halogenated diphenyl-oxides of different isomers and of varying halogen contents is also often desirable inasmuch as such a mixture is liquid at ordinarytemperatures, has a relatively high viscosity and a lower freezing point than the pure component compounds, is more easily soluble in lubricating oils, and has a wide range of activity.

,All of the various halogens are effective when employed according to the present invention but chlorine .is generally preferred inasmuch as it is the least expensive and one of the most effective of the halogens. Bromine and fluorine are more expensive and the latter is diiiicult to handle but they are each usable in accordance with this invention. Iodine is not so easily obtainable as the other halogens and is quite expensive, but it also may be used to provide effective addition agents in accordance with the present invention.

5, It should also be noted that two or more different halogens may be present in the same moleis a complex mixture of chlorine substitution products ranging from the monochlor-up to and including the heptaor octachlor-diphenyl ethers. It is possible, however, to obtain halogenated diphenyl ether containing ten atoms of halogen and 35 this invention is intended to include all of the various halogenated diphenyl ethers, whatever their halogen content. The product may be further refined by treating with solutions of aikalies, or solid alkalies, or alkaline earth oxides,'to re- I) move free acid and decompose such small amounts of addition products as may be present. The resulting product is itself a good lubricant with a high-film strength; and may also be used to improve the lubricating quality, increase the film 85 strength, and inhibit deterioration in use of mineral lubricating all even when added in relatively small proportions.

The chlorinated diphenyl ether, prepared as described above, may be further refined by vacuum 40 distillation. The higher boiling fractions (e. g.

that boiling at 370 C. to 390 C. under atmospheric presure) are extremely stable viscous liquids also having superior lubricating qualities and especlally suitable as lubricants at high tempera- 45 tures where high speeds are encountered (e. g.

turllnes operated with high-pressure superheated steam). The vacuum-distilled product also is a valuable addition-agent for mineral lubricating oils and notably improves such oils for use as g. lubricants in internal combustion engines; e. g.

in lubrication of cylinder walls, valves, valvestems, and crank-shaft and connecting-rod bearloss. It is especially valuable for use in such engines running at high speeds and under high 55 loads, e. g., aircraft engines, Diesel engines, etc.

The formation of chlorine addition products of diphenyl ether is favoredby:

lower temperature (e. g. 100 C. or lower) (2) Absence of chlorine carrie 'whereflieiiowofliquidisinadirectioncounter to that of the gas flow in-a single container; or where, in a multiple-container apparatus, the liquid is advanced toward the source of chlorine.

soastocontainasnbstantialproportionofadditlon products (e. g. a mixture containing about 45% chiorine with rineinthei'ormofad abietoremovethelessstable materialbytreatmentwlthasolnflonofanalkalLorprei'erablya 'ooiid alkaline reisentsuchastheoxideahydroxide orcarbonatesoftheaIkaIiKOraIkaIineearth ,metah. This is conveniently done by-heating one-fourth of the chlo- 13' with crushedfquick-lime" or anhydrous sodium- (3) (miorination by a counter-flow process, e., I

Whm chlorinated-diphenyl ether is Pr pa ed nproducts),itisdesir'- carbonate to a temperature near the maximum temperature to be encountered by the material when in use. For example, for use as an addition to mineral oil to be used as a lubricant for slowspeed bearings, gears, etc., where very high unit pressures are encountered but the maximum temperature is low, the chlorinated diphenyl ether to exceed, say 50 C. For use in a lubricant for high-speed gears, operating under high loads, the alkali treatment should be at a higher temperature, say 100 C. In general, the higher the proportion of addition products in the mixture and the lower the temperature of alkali treatment, the more effective the resulting product as an extreme pressure lubricant or addition agent for increasing the film strength of other lubricants. However, it is advisable to carry out the alkali treatment at a high enough temperature to insure stability in service.

As above indicated, halogenated diphenyl ether may be prepared so as to be especially resistant tov hydrolysis by attaching the halogen directly to a carbon atom which is part of the benzenoid ring structure. However, where operating temperatures of the lubricant are relatively low and film strength is a major desideratum, as in gear lubrication, it is generally desirable that the addition agent contain a substantial amount of halogenation products formed by an addition rather than a substitution reaction since the compounds so formed provide unusually high film strengths. Where operating temperatures are relatively high, as in the ordinary crank-case, or where it is desired to use the lubricant in upper cylinder lubrication, for example, by adding the lubricant to the fuel, it is generally desirable that the addition agent contain only products formed by a substitution reaction since suchproducts are of very high stability while still maintaining good film strength. Such compounds are also more stable than those where the halogen is attached to a side chain.

For further examples of halogenated diphenyl ethers, reference may be had to the application of Dr. CarlF. Prutton, Serial No. 83,976, filed June 6, 1936.

It should be understood that the methods of preparation described above are intended to be merely explanatory and in no wise to limit the scope of the invention. The halogenated diphenyl ether may be prepared in any other satisfactory way, if so desired.

Certain of the halogenated derivatives of diphenyl ether have additional advantages which render them desirable for various uses, for instance, those with longside-chains generally have a greater effect in lowering the pour-point of carboxyl groupmay give increased oiliness as well as greater film-strength to the composition.

The derivatives which contain oxygen-bearing radicles may be classified according to the nature of the attachment of the oxygen to the molecule, viz:-- a i I. Directly attached to one or more carbon atoms,

as in the case of-- (1) Alcohols or phenols (2) Ketones ("i") (3) Aldehydes -C-H i (4) Acids (i) 5) E sters (7) Amides and substituted amides (8) Ethers (6) Salts (9) Compounds with an inorganic radicle where the oxygen is directly attached 5 to a carbon atom: arsenite, hypochlorite, phosphite, thiophosphate,

. thiophosphite, and 3 hydroxyl'amines. II. Directly attached through the means of some other atom, i. e., in the form of an inorganic radicle, e. g.: arsenate, chlorate, chlorite, cyanate, u hydroxylamine, nitrate, nitrite, nitro, nitroso, oxime, perchlorate, phosphate, sulphate, sulphite, sulphinic acid, sulphone, sulphonic acid, sulphoxide, and thio-sulphate. The following table indicates some examples of -oxygen-free radicles which may be included in derivatives of diphenyl ether within the scope of this invention:

The following is a list of a few of the halogenated derivatives of diphenyl ether: halogenated phenoxyphenyl undecyl ketone, halogenated phenoxyphenyl tridecyl ketone, halogenated 1)- methyl phenoxyphenyl heptadecyl ketone, p-chlor phenoxyphenyl heptadecyl ketone, halogenated dixenyl ether, halogenated p-ethyl diphenyl ether, halogenated p-methyl phenoxy phenol. Halogenated products of the type obtained, for example, by condensing diphenyl ether with compounds such as the following and then halogenating; or by condensing halogenated diphenyl ether with such compounds: ethylene propylene, isopropylene, n-butylene, isobutylene, oleic acid, vinyl alcohol, crotonaldehyde, and ethylideneacetone.

The halogenated diphenyl ethers are entirely suitable as an addition agent to such lubricating compositions as greases and bodied oils and perform the same functions therein as in crank-case oils.

In summary, the following improvements in lubricating characteristics arising from the use of the halogenated diphenyl others should be noted: 1) Increased film strength,

(2) Increased stability at high temperatures, (3) Increased oiliness,

(4) Reduced wear,

(5) Increased specific gravity,

(6) Increased flash-point and fire point.

Additional advantages resulting from the use of certain compounds contemplated are:

(7) Lowered cold test, (8) Improved viscosity index. v

It has been found that for most purposes a desirable halogen, or more specifically chlorine content, is equivalent to from about three atoms of chlorine per molecule of diphenyl ether to about eight atoms of chlorine per molecule, an excellent composition containing an average of about six atoms of chlorine per molecule of diphenyl ether. For certain uses where a higher chlorine content is preferred, e. g. where the total amount of addition agent must be limited to a small amount, a chlorine content equivalent to from eight to ten atoms of chlorine per molecule may be used to advantage.

Other modes of applying the principle of our invention'may be employed instead of the one explained, change being made as regards the materials employed in carrying out the process, provided the ingredient or ingredients stated in any of the following claims or the equivalent of such stated ingredient or ingredients be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. A lubricating composition including as a primary lubricating constituent a halogen-bearing derivative of diphenyl ether in a lubricatin oil vehicle.

2. A lubricating composition including as a primary lubricating constituent a chlorine-bearing derivative of diphenyl ether in a lubricating oil vehicle.

3. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition afiecting its use as a lubricant improved by incorporating therein from about 0.1% to about 20%, based on the amount of mineral oil, of a halogen-bearing derivative of diphenyl ether. I l

4. A lubricating composition containing as a principal lubricating constituent a major amount or mineral lubricating oil with the properties of such composition affecting its use as a lubricant improved by incorporating therein from about 0.1% to about 10%, based on the amount of mineral oil, or a halogen-bearing derivative of diphenyl ether.

.5. A lubricating composition containing as a principal lubricating constituent a major amount of mineral lubricating oil with the properties of such composition aiiecting its use as a lubricant improved by incorporating therein from about 0.1% to about 2%, based on the amount of mineral oil, of a halogen-bearing derivative oi diphenyl ether.

6. A lubricating composition containing as a principal lubricating constituent a major amount or mineral lubricating oil with the properties of such composition aiiecting its use as a lubricant improved by incorporating therein from about 2% to about 10%, based on the amount 0! mineral oil, of a halogen-bearing derivative of diphenyl ether.

7. A lubricating composition including as a primary lubricating constituent a halogenated diphenyl oxide containing an amount of halogen equivalent to from 3 to 8 atoms per molecule in a lubricating oil vehicle.

8. A lubricating composition including as a primary lubricating constituent a halogenated diphenyl oxide containing an amount of halogen equivalent to from 8 to 10 atoms per molecule in a lubricating oil vehicle.

9. A lubricating composition including as a primary lubricating constituent a halogenated diphenyl ether containing a substantial proportion or halogen addition products in a lubricating oil vehicle.

10. A lubricating composition including as .a primary lubricating constituent a halogenated diphenyl ether containing a substantial proportion of halogen substitution products in a lubricating oil vehicle.

11. A lubricating composition including as a primary lubricating constituent a halogen-bearing derivative of diphenyl ether having two dit ierent halogens in the molecule in a lubricatingoil vehicle.

12. A lubricating composition including as a primary lubricating constituent a halogenated diphenyl ether which has been treated with alkaii at a temperature higher than the maximum operating temperature of the lubricant in a lubricating oil vehicle.

CARL F. PRU'I'I'ON. ALBERT K. SMITH. 

